SALOME8THE OPEN SOURCE INTEGRATION PLATFORM FOR NUMERICAL SIMULATION

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DEVELOPMENT FACT SHEETProject kick off: 2001Development team: 20 engineersLicence: LGPLDistribution: Most Linux distributions and Windows® operating systemsBug tracking: 500 fixes and improvements per yearVerification & Validation: automated test procedure with 6000 testsUsers: 300 users at EDF and CEA, 50000 downloads this year

The SALOME platform is an open source software framework for the integration of numerical solvers in various scientific domains. CEAand EDF are using SALOME to perform a wide range of simulations, which are typically related to industrial equipment in power plants(nuclear power plants, wind turbines, dams... ). Among primary concerns are the design of new-generation reactor types, nuclear fuelmanagement and transport, material ageing for the life-cycle management of equipment, and the reliability and safety of the nuclearfacilities.

To address these challenges, SALOME is integrating a CAD/CAE modelling tool, industrial mesh generators, and advanced 3D visualizationfeatures.

SERVICE AND SUPPORTOPEN CASCADE provides a wholerange of services around SALOME,for professional end-users, such astechnical support and specifictraining.

The “à-la-carte” support programis particularly suited for universitiesand academic organizations, as wellas industrial companies:

Helpdesk & technical support forexpert needs concerning a one-shot technical issue, delivered bymail or by phone within a guar-anteed time frame.

Expert consulting delivered onthe end-user premises by one ofthe SALOME experts.

Bug corrections & improvementsfor specific needs or complexproblem solving.

Creation of Geometries andMeshes (geometric modelling,Meshing, data input) for the exe-cution of numerical simulationstudies.

SALOME Training allows most offundamental and advanced func-tionalities of the platform to bemastered.

For more details, consult:http://www.salome-platform.org/service-and-support

KEY FEATURESIn order to accurately simulate com-plex industrial systems, scientistsand engineers need to integratemost fields of physics such as

material science, solid mechanics,structural dynamics, fluid physics,thermohydraulics, nuclear physics,radiations or electromagnetism. TheSALOME platform gathers all thesefields in one single simulation envi-ronment.

The main features of the SALOMEare:

Design of the geometricrepresentation for physical sys-tems (CAD modelling) and itsassociated discretized model(meshing functions for finite ele-ments or finite volumes solvers).

Ability to integrate domainspecific solvers into normalizedsoftware components with stan-dard interfaces to facilitate thecoupling of different physicaldomains.

Supervision of computationworkflows defined as graphsof distributed software compo-nents, including CAD modelling,domain specific solvers and dataprocessing components.

Analysis of simulationoutput, in particular using visu-alizations of physical fieldsresulting from computationworkflows in 3D views or in plotcharts

In this context, one of the key pointsof the platform is the usage of stan-dardized data models to describephysical concepts for numericalanalysis, and to ensure interope-rability between software compo-nents. For instance, the MED datamodel is used for meshes and fieldsdescriptions.

MODEL OFDEVELOPMENTThe SALOME platform is activelydeveloped by CEA and EDF, twokey players in the French energyindustry, and with the support ofthe Capgemini subsidiary OPENCASCADE, one of the leaders insoftware development for scientificcomputing. This 15 years old part-nership provides SALOME projectwith a very committed and dedi-cated team specialized in scientificcomputing.

Moreover, the SALOME platformheavily relies on the integration ofcutting edge third party softwareprograms: the commercialadvanced and robust meshing pro-grams MeshGems-CADSurf andMeshGems-Tetra (by DISTENES.A.S.) and ParaView including theVTK 3D visualisation toolkit (by theKitware Inc.).

DOWNLOAD THESALOME PLATFORMThe SALOME platform is availableunder LGPL licence and can bedownloaded from the web site:http://www.salome-platform.org forseveral LINUX distributions andWindows. The site provides tutorials,a forum section and gives access tothe user documentation and thesource code.

Figure 1: Screenshots of thepublic web site of SALOME.www.salome-platform.org

SALOME8PLATFORM

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The SALOME platform allows the integration of specificsolvers and graphical user interfaces to create engineering-specific simulation applications. For example, SALOME-MECAprovides a simulation environment for solid and structure mechanics,based on the Code_Aster solvers. At EDF, this application is used tostudy ageing equipments, reliability and safety issues of nuclear vessels,turbine vibrations and much more.

The SALOME-HYDRO platform isan example of application dedicatedto free-surface hydraulic analysis.The screenshot (see Figure 2) illustrates modeling of a river frombathymetric data using the platform.

Figure 2: River model from bathymetric data using SALOME-HYDRO (EDF/R&D)

Figure 3: Illustration of the ALAMOS application dedicated to the modelling of nuclear reactors(CEA/DEN)

The last example (see Figure 3) is aSALOME based application namedALAMOS, which is dedicated to themodelling of nuclear reactor forthermo-nuclear analysis.

In this context, SALOME is dis-tributed with the same QualityAssurance as any industrial process,including Verification and Validation.The development team providestop-level services and support tobuild dedicated applications.

DEVELOPINGDOMAIN SPECIFICAPPLICATIONS

Analysis of the rotor of apower generator (EDF/R&D)

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GEOMETRICMODELLING The CAD module (known asGEOM) provides a rich set of func-tionalities to create, edit, import ormodify CAD models. The geometricshapes may be designed interac-tively using the Graphical UserInterface (GUI) or the Text UserInterface (TUI) through Pythonscripts. All GEOM functionalities areavailable in both GUI and TUI. Thisallows complex shapes or severalconfigurations of a shape with different values of its parameters to be built. This enables the user toparameterize its geometry and playdifferent scenarios without anyeffort.

The geometric kernel of GEOM isbased on Open CASCADETechnology which provides aboundary representation of themodel (BRep) and maintains thetopological structure required bythe subsequent meshing operations.

SALOME is capable exchanginggeometry with other CAD systemsusing formats such as STEP, IGES,BREP (the Open CASCADE nativeformat) and XAO (to deal withgroups and fields on geometry).

MESHING THE GEOMETRYThe meshing module known asSMESH provides a wide range ofalgorithms particularly suited forfinite-element and finite-volumemethods. A mesh can be dividedinto groups to segregate differentregions of the geometry. It allowsdifferentiation between mesh properties or even between meshtypes (hexahedral or tetrahedral).Group naming provides the identi-fication of local boundaries andinitial conditions, and facilitates themesh visualization or other post-processing operations (see Figure4).

Mesh moduleA complete toolbox enables theuser to check the mesh quality andto perform local modification oradjustment. Transformation oper-ations can be used to producecomplex meshes or compounds.

Like the CAD process, the meshingprocess can be entirely handled by Python scripting to ensure fullreproducibility and parameterizationof the simulation workflow.

Figure 4: Modelling of the rotor of a power generator (EDF/R&D)

Figure 5: Modelling of the volume around a circular singularity for fluid flow analysis (CEA/DEN)

MODELLING PHYSICAL SYSTEMS

SALOME provides several modules to create complex geometrical models. These include high levelmeshing functionalities to prepare numerical models that fit the solver requirements.

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Hybrid meshesSALOME provides a specific meshalgorithm to create hydrid meshes(see Figure 6), mixing tetrahedraand hexaedra. This tool is based onthe MeshGems-Hybrid component(from DISTENE S.A.S.).

MeshGems-Hybrid is generalizingthe automatic conformal volumefilling for all closed tri-quad surfacesgiven as an input, by mixingtogether the methods ofMeshGems-Tetra and MeshGems-Hexa in addition to an Extrusionmethod. And, as a subset of thewhole set of MeshGems-Hybridcapabilities, Boundary Layers canbe generated automatically(www.meshgems.com/volume-meshing-meshgems-hybrid.html).

Optimization and refinementSMESH is completed with the HOMARD® module that per-forms local mesh adaptationsrequired by numerical codes tomeet accuracy and performance.

To improve the quality of the simulations, local mesh adaptationsoffer an efficient compromisebetween a fine mesh and a lowcomputational cost. HOMARD®

allows refinement and coarseningoperations to adapt the mesh,according to the numerical error ofthe simulation.

Catalog of meshing algorithmsThe SALOME platform integrateseither open-source meshing toolssuch as NETGEN (https://source-forge.net/projects/netgen-mesher)and GMSH (http://gmsh.info), orcommercial ones such asMeshGems-CADSurf and MeshGems-Tetra edited by DISTENE S.A.S(www.distene.fr).

These powerful meshing tools arebased on different algorithms andproperties (local size, growth rate,enforced vertices... ) that can beadjusted to get the best meshquality for each specific numericalsimulation.

These different meshing algorithmscan be combined in SALOME. For example, the 2D trans-patchmeshing algorithm from GMSH canbe used for the boundary surfacemesh together with the 3DMeshGems-Hybrid algorithm forthe internal volume (see illustrationbelow).

Hexahedral meshesSALOME provides specific meshalgorithms that help to create com-plex models with hexahedral meshrepresentations. This kind of meshis specifically required for somenumerical solvers, for examplestudies involving fluid dynamicssolvers.

SALOME provides several tools tosolve this problem. The HEXA-BLOCK module can be used todefine a topological description iso-morphic to the real geometry andfrom which a hexahedral mesh canbe automatically generated. TheMeshGems-Hexa SMESH plugin isa wrapper of the commercial meshprogram edited by the DISTENES.A.S. This function can create auto-matically a hexahedral mesh of acomplex geometry without any partition of the solids.

Figure 6: SALOME can combine different meshing algorithms. Inthis example, the 2D trans-patch meshing algorithm from GMSH isused for the boundary surface mesh while the 3D MeshGems-Hybrid algorithm is used for the internal volume to get a globallyhexahedral mesh.

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SALOME provides a set of servicesto create a simulation workflow thatconnects different computationunits. Then it executes this workflowon a distributed network of computers and HPC resources.

The main features are:

The possibility to integratedomain specific solvers asnormalized components withstandard interfaces to ease thecoupling of different physicaldomains. These SALOME components can be used as thecomputational units of a simula-tion process. Some tools areprovided to automatize this integration for standard configu-rations (integration of executableprograms, functions of a libraryor python scripts).

The supervision of a compu-tation workflow defined as agraph of connected SALOMEcomponents, including CADmodelling, meshing, domain specific solvers and data processing components (seeFigure 7). The graph can beedited using a graphical userinterface (GUI) or the Python TextUser Interface (TUI) to handlecomplex workflow into scripts.

The distribution on HPCresources. SALOME contains ajob manager that can be used todefine a computation job(including either a simpleSALOME component or a com-plete workflow) and to drive thesubmission of the job to a dis-tributed set of computers or HPCresources. The job manager canhandle many batch systems likePBS, LSF, SGE, LOADLEVELER orSLURM through a normalizedgeneric interface. It comes witha GUI but can be used at a pro-gramming level using a C++ orPython interface to create simplescripts or domain specific tools.

The design of numeric experimental plans. SALOMEprovides you with a schedulerthat helps the user to managethe parametric computation (seeFigure 8). The input data are theexperimental plan (typically csvdata) and the computation unit(deterministic function). It can beused together with advancedmodules such as OPENTURNSthat helps you design the input experimental plan and theanalysis of output results (meta-modelling, statistical analysis,uncertainty quantification).

Figure 8: Design of numeric experimental plans anddistribution of computation units on HPC with failovermanagement (EDF/R&D

SUPERVISION OF COMPUTATIONWORKFLOWSThere is an increasing need formultidisciplinary parametric simulations in various researchand engineering domains. Fluid-structure interaction andthermal coupling are two exam-ples. The software strategy inmany contexts of simulation (atleast at CEA and EDF) is todevelop numerical solvers dedi-cated to their own domain, andthen to execute multi-domainssimulation by coupling these specific solvers.

Figure 7: Typical example of a simple computing data flow includingCAD, mesh, physical solver and data postprocessing (EDF/R&D)

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PROCESSINGSIMULATION DATASETBeyond the processing and visuali-zation of meshes and data fields,the SALOME platform containsadditional modules dedicated toadvanced data analysis:

Data assimilation and opti-misation environment, forexample to recalibrate theparameters of a model by comparison of the simulationdata to experimental measures(modules ADAO, URANIE)

Propagation of uncertaintiesin the simulation workflow, forexample to evaluate the uncer-tainty of the resulting dataconsidering a given uncertaintyon the input parameters (modules OPENTURNS, URANIE).

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ANALYSIS OF SIMULATIONDATA

Figure 9: Visualizationof the fluid flowaround a circularsingularity (CEA/DEN)

Figure 11: Visualization of thermohydraulics results using PARAVISin remote mode (EDF/R&D)

PROCESSING FIELDSAND MESHESInside SALOME, the MED datamodel defines a normalized repre-sentation to describe meshes of thegeometry and fields of the physicalvalues of the simulation. This datamodel is a key feature that helpsspecific solvers to take advantageof SALOME services.

It comes with a software implemen-tation (the MED-file library) for filepersistence and serialization inmemory for inter-communicationof simulation data between components.

Based on concepts from MED datamodel, the MED module providesa full set of services for high per-formance data processing. It includes the MEDCouplingpackage which implements meshesand fields C++ classes fully wrappedin python. MEDCoupling also provides a large set of methods tohandle efficiently in memory allfields and meshes objects (interpo-lation, algebraic operations, fieldextractions, integration,…) andallows to easily exchange fields andmeshes between processes (directlyin memory or using files).

VISUALIZATION OFSIMULATION RESULTSPhysical solvers generate results thatcan be analysed within the ParaViSmodule. This module has beendeveloped to integrate ParaView(third party software edited byKitware and based on the VTKtoolkit) into SALOME, and to offerall the functionalities of this award-winning post-processor tool.

A wide range of representations areavailable to explore the datasets:surface, volume, gauss points... Thedata can then be analysed usingmany filters to extract significantdata: clip, threshold, iso-surface,stream lines, elevation surfaces (seeFigure 9).

Quantitative information can beextracted using the data analysistools: taking a selection of the data,histograms, plots over time or curvi-linear abscissa are one click away.

All these features can be animatedwithin the module to analyse time-varying data, sweep a cutting planethrough the dataset, or animate thedeflection shapes of a modal analysis (see Figure 10).

This module is fully scriptable inPython to create visualizations inbatch when necessary or to repeatanalysis on parametric runs. It isused on remote visualization clustersto interactively analyse largedatasets (see Figure 11).

Figure 10: Crystal growth simulation using Lattice Boltzmannequation (CEA/DEN)

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CONTACT US:Francis Kloss francis.kloss@cea.frGuillaume Boulant guillaume.boulant@edf.frMikhail Kazakov mikhail.kazakov@opencascade.com @

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EDF - R&DEDF Lab Paris-Saclay7, boulevard Gaspard Monge91120 PALAISEAU, Francewww.edf.com

Open Cascadegroupe Capgemini,1 place des frères Montgolfier78044 Guyancourt Cedex, Francewww.opencascade.com

Commissariat à l’Energie Atomique et aux Energies Alternatives, CEA-Saclay, DEN, DM2S, 91191 Gif-sur-Yvette Cedex, Francewww.cea.fr

salome-platform.org

2016

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